so the good news is the weather looks great for Sunday, the bad news in when I rang the Barge they could only reserve us a table inside (they also said by 2pm the garden is usually rammed). With this in mind I have decided to change the location to the Swan Inn in milton keynes village. It looks lovely and has an award winning pub garden AND they can guarantee us outdoor seating.
I hope this is OK with all. Looking forward to seeing you at 2pm on Sunday =)